The present invention generally relates to new and improved disposable nonwoven laminates and new and improved methods for making them, as well as, to new and improved surgical drapes and gowns comprising the new and improved disposable nonwoven laminate materials. More particularly, it relates to new and improved disposable multi-ply surgical laminates including nonwoven layers in which plies of the laminate are bonded in a special flexible manner to provide materials having improved softness, hand and drapability and in which the desired material properties of layers are better retained and expressed to provide more satisfactory products.
Surgical drapes and gowns have been used to maintain a sterile field in surgery. Surgical gowns have been used in the medical community to protect health care professionals from liquids and micro-organisms during surgical and other procedures. Single use surgical gowns are typically made of nonwoven, disposable fabrics. Such gowns typically include a single body panel or multiple panels including a front panel, a pair of back panels which are connected to the sides of the front panel and extend away from the front panel, and a pair of sleeves which are provided at the juncture of the front and side panels. The front panel covers the front of the health care professional during the procedure. The back panels are secured around and overlap each other to cover the rear of the health care professional and a tying structure. Typical surgical gowns will include two outer ties and two inner ties. The inner ties are utilized to secure the inside back of the gown. The outer ties are used to ensure that the back of the gown overlaps around the rear of the health care professional.
Sterile surgical drapes are also known and widely used to create a sterile surgical field and to protect the patient. Surgical drapes come in a variety of shapes and sizes and many specialized drapes adapted for a particular type of surgery have been adopted. By way of illustration, these drapes may be provided in a rectangular sheet form for draping the operating table, covering an anesthesia procedure area, or covering the patient""s legs or abdomen. More specialized drapes may include leg holes or arm holes as required for different procedures so that some portions of the patient""s body remain unexposed under the drape and other portions are exposed overlying a different section of the drape. Some drapes are provided with openings or windows called fenestrations to define a bounded area around an incision site. Fenestrated drapes may have extra absorbent layers around the perimeter of the openings. Surface treatments may be used to render portions of the drapes antibacterial, antimicrobial, and/or waterproof as desired in particular surgical procedures. Simple rectangular drapes may also be used as absorbent surgical towels or wipes. Finally, the drapes may include different types of panels secured together. For example, a table drape may include a thicker absorbent table top panel and a plurality of attached side panels which have a thinner less absorbent construction to act simply as a splash guard for or to provide a barrier with respect to the underside portions of the table.
Earlier surgical drapes and gowns were constructed of woven natural fabric materials, usually cotton. These cloth articles were sterilized in the autoclave in preparation for surgery. Alternative fabrics comprising synthetic fibers were added and used. Eventually, with the advent of nonwoven fabric materials, drapes and gowns comprising nonwovens were used to provide disposable gowns and drapes adapted for one time use.
Previous drapes and gowns prepared from nonwoven materials suffer from a number of drawbacks. Typically, the nonwoven web layers are assembled with a film layer to provide a fluid impervious laminate material which is used to fashion the surgical gown. Hot melt adhesives have generally been applied over substantially the entire surface of one of the layers to bond the web and film layers together to provide the laminates. These laminates are characterized by board-like stiffness and poor drapability which makes them uncomfortable for the medical personnel who wear them. Sleeves made from these fabrics do not conform well to the wearer""s wrist and frequently permit body fluids to travel along crinkled channels at the wrist under the glove cuffs and against the wearer""s skin which is unacceptable. Moreover, the films used to provide an effective fluid barrier, are generally not breatheable and accordingly, gowns made from these laminates can be unbearably hot for the surgical personnel who must wear them.
Efforts to improve the softness and cloth-like quality of these nonwoven surgical laminates has lead some manufacturers to try intermittent thermal bonding of the layers through heat and pressure rollers, or ultrasonic welding techniques. The heat and pressure bonded types are undesirable because the nonwoven layers are crushed and fused in the process which detracts from their desired properties such as loft, flexibility and softness. The melt bonding points are rigid and do not bend and flex, so that the overall softness, feel and drapability properties of these materials is better but still not as good as desired. Moreover, heat bonded laminates may only be formed from appropriately heat matched thermoplastic materials, which limits the types of material layers that can be used to form the surgical laminates, placing unwanted limits on product design and ultimate product qualities.
Unexpectedly, in view of the foregoing, it has now been discovered that new and improved disposable nonwoven surgical laminates may be provided using dramatically reduced amounts of adhesive arrayed in a special bonding arrangement to provide improved disposable nonwoven surgical laminates having improved softness, hand, drapability, and comfort characteristics. In greater detail and in accordance with an embodiment of the present invention, a new and improved disposable laminate comprises a film layer, at least one nonwoven web layer and a plurality of spaced apart unbounded adhesive clusters. Each adhesive cluster comprises a plurality of discrete, spaced apart droplets of adhesive securing the film layer and the web layer together. Preferably, the adhesive clusters are spaced in a regular repeating pattern which extends the length and width of the laminate.
By unbounded is meant that the adhesive clusters do not include any applied linear boundary or perimeter of adhesive defining the cluster area. Each cluster is a perimeterless grouping of spaced apart droplets. Each cluster area is flexibly foldable in all directions with respect to the plane of the laminate which is believed to contribute to superior hand and drapability for the new and improved laminates. The low adhesive content and flexible bonding methods permit the overall softness and other desired web properties, such as absorbency, to be maintained in the laminating process and to be retained and more fully expressed in the finished laminates and products.
The film layers are preferably thermoplastic materials capable of withstanding gamma sterilization. Preferably, the thermoplastic film layers form a satisfactory fluid impervious layer capable of preventing fluid and pathogen transfer between surgical personnel and patient through the laminate. The films may be breatheable or non-breatheable. Illustrative thermoplastic films which may be used to provide the film layer include polyolefins, polyolefinic copolymers, polyesters and copolyesters to name but a few. The thermoplastic films may be made from substantially any film forming thermoplastic material suitable for close to the skin use which may withstand commercial sterilization procedures.
In a preferred embodiment, the thermoplastic film layers comprise breatheable impervious thermoplastic films selected from monolithic thermoplastic films or microporous thermoplastic films. Especially preferred films are monolithic thermoplastic copolyester elastomer films. Polypropylene based films are less preferred due to their instability under gamma sterilization processing. The film layers may generally have a basis weight of from about 0.25 to about 5.0 ounces/square yard and have a film thickness of from about 0.25 mil to about 3 mil.
The nonwoven web layers are preferably but not necessarily thermoplastic materials which can also withstand gamma sterilization processing. The nonwoven webs may be wet laid, dry laid, spunlaced, adhesive bonded, thermal bonded or spunbonded-melt blown-spunbonded (SMS) nonwoven web types. The webs may be made of thermoplastic fibers, regenerated fibers, natural fibers, and so-called bicomponent or sheath-core fibers, and may comprise mixtures of any two or more of the foregoing fiber types. The nonwoven webs may have a basis weight of from about 0.25 oz./sq. yd., to about 4.0 oz./sq. yd.
In an embodiment, the adhesives used in the laminates also comprise thermoplastic adhesives, thermosetting adhesives and/or crosslinked adhesives which can withstand gamma sterilization. Illustrative thermoplastic adhesives include olefinic polymer and copolymer adhesives, such as ethylene vinyl acetate, styrene, maleic anhydride modified polyethylene or polypropylene; polyamide adhesives, polyester and polyurethane adhesives. Illustrative thermosetting adhesives may include (meth)acrylic adhesives or styrenic adhesives to name but a few. Other adhesives conventionally employed in the field of nonwovens may also be used.
In an embodiment, new and improved two-ply laminates are provided including the film layer and a single web layer cluster bonded together. In an alternate embodiment, new and improved three-ply laminates are provided comprising a thermoplastic film layer having first and second opposed major surfaces, a first thermoplastic nonwoven web layer disposed adjacent the first major surface, a second thermoplastic nonwoven web layer disposed adjacent the second major surface, and a plurality of spaced apart unbounded adhesive clusters of spaced apart adhesive droplets securing the first web layer to the first major surface and securing the second web layer to the second major surface. In the new and improved three-ply or triplex laminates the first and second webs may be the same or different. Preferably, the film layer is a breatheable impervious thermoplastic film and the first and second nonwoven web layers comprise different web materials.
In accordance with another aspect of the invention, the present invention provides, in an embodiment, a new and improved method for making a disposable laminate. The method comprises the steps of providing a nonwoven web having a major surface and having an associated length dimension and a generally perpendicular width dimension. A plurality of discrete spaced apart droplets are deposited onto the web surface in such manner that pluralities of spaced apart droplets are arranged on the web surface in perimeterless clusters. Moreover, a plurality of these clusters are deposited on the web surface in a spaced apart manner extending generally over the length and width of the web surface. The web surface and adhesive droplets are contacted with a surface of a film layer to bond the film layer and the web layer securely but flexibly together to form the disposable laminate. In a preferred embodiment, the unbounded clusters of adhesive droplets are deposited in a regularly repeating pattern or array of adhesive clusters.
In an embodiment, droplets of adhesive are deposited in a specially arranged manner onto the web surface by providing an etched gravure roller having discrete spaced apart droplets of adhesive disposed in regular depressions defined in a circumferential surface thereof. An elastomer covered pressure roller having a circumferential bearing surface is also provided. The bearing surface of the pressure roller has a plurality of relatively raised island-like contact surfaces separated by a plurality of grooves. The pressure roller is positioned adjacent the gravure roller to form a nip therebetween so that the raised contact surfaces of the pressure roller make pressing contact with portions of the circumferential surface of the gravure roller. The grooved portions in the bearing surface of the pressure roller do not make contact with the circumferential surface of the gravure roller.
The gravure roller and pressure roller are rotated and the nonwoven web is passed into the nip between them. A portion of the spaced apart droplets of adhesive are transferred from the depressions in the gravure roller surface onto the first web surface. Spaced apart clusters of spaced apart droplets of adhesive are transferred in this manner onto the first web surface corresponding only to those surface areas of the second surface of the web which are pressingly contacted by the raised contact surfaces of the pressure roller.
In an embodiment, the raised contact surface portions on the pressure roller can be arranged in a regular pattern of spaced apart columns and spaced apart rows of raised contact surfaces. Typically, the pressure roller will have a generally cylindrical configuration including a core longitudinal axis. In a preferred embodiment, the repeating pattern of raised contact surface portions is disposed on the surface of the pressure roller in an angled manner such that a given row of raised contact surfaces is helically offset with respect to the core longitudinal axis. This deployment of contact surfaces facilitates a smoother more accurate transfer of adhesive clusters with less vibration and chatter.
Droplets of adhesive may be provided in the depressions on the gravure roller surface by submerging a portion of the gravure roller surface in a reservoir of adhesive. Excess adhesive may be removed from the surface of the gravure roller from all but the depressions with a doctor blade. The adhesive reservoir and doctor blade are disposed at a position along the path of rotation of the gravure roller located before the nip point where the pressure roller contact surfaces make contact with the surface of the gravure roller.
In an alternate method, when using difficult to adhere films or relatively temperature sensitive nonwoven web materials, it may be preferable to deposit the adhesive droplets onto the film surface instead of the web surface. This may be achieved by reversing the positions of the rolled film and rolled nonwoven web supplies.
In still another aspect, the present invention provides, in an embodiment, new and improved disposable surgical drapes and gowns comprising the new and improved laminate materials. The drapes comprise a piece of a disposable laminate in accordance with an embodiment of this invention and may include fenestrations and one or more panel elements secured to the laminate panel adjacent a fenestration or adjacent a peripheral edge of the laminate panel.
In an embodiment, new and improved surgical gowns are provided comprising a body portion and two sleeves connected to the body portion. The body portion includes a front panel and two opposed back side panels connected to the front panel. A tie member is attached to the body for securing the gown in a closed position on the wearer. The sleeves, the body portion or both comprise a disposable laminate in accordance with an embodiment of this invention. In a preferred embodiment, the body and sleeves are made from a breatheable impervious disposable laminate as described herein. Alternatively, single panel surgical gowns comprising a new and improved disposable laminate in accordance with this invention are also fully contemplated herein.
A major advantage provided by the new and improved laminates, drapes and gowns in accordance with embodiments of this invention is that these products exhibit improved softness, hand and improved drapability in comparison with commercially available drapes and gowns.
Another advantage provided by the new and improved laminates and gowns is that they exhibit improved conformability to application so that undesirable channeling of fluids under surgical gloves is substantially reduced or eliminated.
A further advantage provided by the laminates, drapes and gowns in accordance with the present invention is that they are characterized by improved aesthetic qualities having a pleasing appearance and texture.
Still another advantage provided by the laminates and finished articles in accordance with embodiments of this invention is that dramatic reductions in the amount of adhesive afford the possibility of increased chemical absorption. For example, higher percentages of unbonded portions of the nonwovens may realize their full power of absorbency.
Still a further advantage provided by the laminates and articles in accordance with embodiments of this invention is the possibility of increased mechanical absorption of fluids because the more open three dimensional configuration captures additional fluids.
Other advantages provided by the present invention will become apparent from the following Detailed Description and Illustrative Drawings, in which: